I have a 2000 Blazer 2dr 4x4
ac works, heat works but it seems to be stuck in the middle zone( main vents). It will not change to floor or defrost, either on heat or a/c. I do hear a small vacuum leak under the dash. Was looking for some advice before i start tearing dash apart. Any help will be greatly appreciated........

 

If Christine 208 does not answer, PM her and shell get you on the right track

George

 

im having the same problem there to also with transmission shift solid b two transmissions same problem

 

These vacuum systems can be annoying.

The first thing to check is if the vacium hoses in the engine compartment are in good shape. I have a link below for checking and replacing those hoses.

As for the under-dash hoses, those are plastic and more durable and if you are hearing what sounds like air leaking, I would guess that the hoses likely became disconnected from the diaphragm actuators. Some of these can be accessed without taking the dash apart.

If the diagrams for the HVAC vacuum hoses are not in my thread below, reply back and I'll try to find them.

Good Luck